THE OUTDOORS DIGEST | FIELD GUIDE

Blue whale

It was someone's small joke to give the planet's largest organism the scientific name "musculus," meaning little mouse. Perhaps no other word could convey the immense proportions of an animal that grows to more than 100 feet -- longer than a jumbo jet, with a heart the size of a Hyundai -- and that requires up to four tons of food per day. An estimated 2,000 to 3,000 blue whales congregate along the California coast from midsummer until mid- or late October to gulp down stupendous concentrations of the tiny shrimp-like krill that gather here. For these few exciting months, it is possible to watch blue whales feeding close to shore between Point Reyes, north of San Francisco, and the Channel Islands. Then the whales head back out to sea and continue south, alone or in pairs, to their wintering spots near Costa Rica and the Gulf of California.

NATURAL HISTORY

Hunted nearly to extinction by the 1960s, blue whales have made a modest comeback along the California coast but remain rare in other oceans. Wandering vast distances, they keep in touch with piercing calls -- at 188 decibels, louder than a jet engine -- that carry hundreds of miles.

KEY CHARACTERISTICS

Varying shades of pale mottled blue and their size distinguish these whales. When surfacing, they display a small triangular fin far back along the body